I came across the following question:

$\ce{XeF4}$ on reaction with gaseous nitric oxide forms xenon gas and (P). Find the total number of lone pairs present in one molecule of P.

As far as xenon chemistry is concerned, I just know that xenon fluorides undergo hydrolysis giving different products like Xe, $\ce{XeOF4, XeO2F2, XeO3}$.

I have no idea that xenon fluorides even react with nitric oxide. I did a lot of digging on Google but could not find a single source/article discussing about the reaction of xenon fluorides with nitric oxide or the other way round.

I would be glad if someone can tell about the products of the given reaction with a link to the source. The answer the question is given as '6 lone pairs'.


1 Answer 1


I have no idea that Xenon Fluorides even react with nitric oxide.

Xenon fluorides do in fact react with nitric oxide. Following is the abstract of a 1964 paper(See ref.):

The rate of reaction of $\ce{XeF4}$ and $\ce{XeF2}$ with $\ce{NO}$ and with $\ce{NO2}$ has been studied between $\pu{300° - 350°K}$ at pressures between $\pu{0.1 - 30 mm}$. The second‐order rate constant at $\pu{300°K}$ and the activation energies are, respectively: $\ce{XeF4 + NO}$, ($\pu{3 liters/mole sec, 7 kcal/mole}$); $\ce{XeF2 + NO}$, ($\pu{0.3 liters/mole sec, 10 kcal/mole}$). The rate of $\ce{NO2}$ with $\ce{XeF4}$ and $\ce{XeF2}$ was too slow to observe, $\pu{k < 0.01 liter/mole sec}$. The fluorides of xenon react with the oxides of nitrogen much more slowly than $\ce{F2}$ reacts with $\ce{NO}$ or $\ce{NO2}$. By means of a Polanyi—Semenov plot, the reactions of $\ce{XeF4, XeF2}$, and $\ce{F2}$ with oxides of nitrogen were combined to give an estimate of the successive dissociation energies of $\ce{XeF4}$, which are (kcal/mole): $\ce{XeF4→XeF3 + F (48)}$; $\ce{XeF3→XeF2 + F (15)}$; $\ce{XeF2→XeF + F (54)}$; $\ce{XeF→Xe + F (11)}$. From these kinetic and thermochemical data a strong case can be made for the stepwise reduction of $\ce{XeF4}$.

Ref.:Reaction Rates of Xenon Fluorides with Oxides of Nitrogen by Harold S. Johnston and Robert Woolfolk, J. Chem. Phys. 41, 269 (1964); DOI: 10.1063/1.1725632

  • $\begingroup$ @ Nilay Ghosh. So basically the Fluorine atoms react to form $F_2$, which has 6 lone pairs. Thanks a lot. $\endgroup$ Commented Jul 10, 2021 at 9:34
  • 1
    $\begingroup$ @AmmaarahFatima Yes, fluorine is a byproduct although most of them further reacts with remaining nitric oxide to form nitrosyl fluoride $\endgroup$ Commented Jul 10, 2021 at 9:39

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